Piper SeminolePiper Seminole

Overview

The New Piper's Seminole began life about 30 years ago as one of a new breed of multiengine trainers. It was built with an eye toward safety. In the light twin's glory years of the 1950s and 1960s, flight instructors and designated examiners had little federal guidance on practical test standards. In attempts to provide real-life engine-out experiences, some instructors used poor judgment and went too far. Hair-raising drills such as engine cuts right after takeoff, stalls with a windmilling engine, and engine-out stalls in turns sometimes made engine-out practice all too real. Multiengine training accidents began to mount.

One reason why earlier multi-trainers tended to bite back has to do with their behavior near VMC. VMC — defined as the minimum airspeed at which directional control can be maintained with the critical engine inoperative — in pre-Seminole days meant uncommanded rolling and yawing at airspeeds well above the stall.

Students practicing their VMC demonstrations would put the left, or critical, engine (the one that, were its power lost, would create the most adverse handling characteristics) at a zero-thrust setting, advance the right engine to full power, then reduce airspeed by pitching up. At or near VMC — marked by a red radial line on the airspeed indicator — students would begin to notice the onset of an uncontrollable roll and yaw toward the "dead" engine, in spite of full opposite rudder. If not caught in time, or if the loss of control happened suddenly, or if the student botched the recovery by letting airspeed bleed off or leaving the good engine's power on, the result could be a roll to the inverted. Sometimes this ended with fatalities, especially in cases where instructors cut an engine right after takeoff and students allowed airspeed to drop to VMC — or lower.

By the late 1970s, Piper and Beechcraft decided to tame VMC by installing counterrotating propellers on their new multi-trainers. This eliminated the critical engine and lowered VMC. In the Seminole's case, VMC is 56 KIAS — just one knot above the 55-knot stall speed in the landing configuration and one knot below the clean stall speed.

Never mind that the Wright brothers used counterrotating propellers on their historic 1903 Flyer. Counterrotating propellers were billed as a newly discovered antidote to the VMC rollover, and they caught on. The reduced p-factor and lift moments from the right propeller — thanks to its "new" counterclockwise rotation design — meant less violent rolling and yawing at VMC, or any other asymmetric-power condition. Do a VMC demonstration below 4,000 feet msl or so in a Seminole, and you're much more likely to approach a conventional stall before any dangerous rolling sets in. Above 4,000 feet, the airplane may not be as polite. Stall speed is a constant, but VMC decreases with altitude because asymmetric thrust decreases with altitude. At some point, VMC falls below stall speed. Enter a stall with asymmetric power above that altitude, and you could be faced with a potentially nasty stall, one with a dangerous roll-yaw combination.

But the fact remains: Seminoles continue to be one of the tamest, friendliest light twins ever built. Major aviation schools top the list of big-volume customers. Some of the schools that use Seminoles as their flagships include: Embry-Riddle Aeronautical University (18 Seminoles); FlightSafety International (25); University of North Dakota (14); Pan Am Academy (17); Delta Connection Academy (seven); and the biggest operator — Airline Transport Professionals Inc. (ATP) — with a whopping 76 Seminoles. The overseas market is strong, too. I once ferried a Seminole all the way to Bangkok, Thailand, where it now serves in a military flying club.

The Seminole is designed with simplicity in mind. The fuselage and wings are virtual clones of Piper's Arrow single-engine retractable, which explains why some call the Seminole a "Twin Arrow." The flaps are mechanical, and are actuated by the same stone-simple floor-mounted hand lever used in scads of earlier Piper singles, as well as the new 6X and 6XT. Two 55-gallon fuel tanks (protected by firewalls) live in huge nacelles behind the engines, and there are only three fuel selector positions: On, Off, and Crossfeed.

Beginning with the 2000 model year, New Piper made some really nice improvements over the original design. The panel is clean and uncluttered, with a Garmin GNS 430 GPS/nav/com as standard equipment. A horizontal situation indicator (HSI) and second GNS 430 are part of the very popular optional avionics package.

The propellers' unfeathering accumulators are other great standard features of newer Seminoles. These store oil pressure, then release it to the prop hub when you want to unfeather an engine. To do an airstart, all you do is advance the prop lever at the appropriate airspeed (100 to 120 knots) and the accumulators start the props turning. Sure beats the old design, which calls for using the starters to uncage the props.

As an instrument flying platform, the Seminole is exemplary. Thanks to the T-tail there's little in the way of pitch changes and retrimming requirements with configuration changes. Use the proper target values and the airplane behaves well during instrument procedures. Cruise speed? Single-engine climb performance? Range? These values are about what you'd expect from a light piston twin. The book says you can see speeds as high as 168 KTAS at 75-percent power, but in my experience this is often optimistic. Single-engine climb, posted as 212 fpm, is as lackluster as any light piston twin. But with temperatures below standard and a light load, you can see single-engine climb rates pushing 400 fpm. Single-engine work? In spite of the counterrotating engines there's more than enough asymmetric thrust to give students strong legs.

Landings are uncomplicated, and using short-field techniques (full flaps, 75 KIAS or slightly less over the fence, depending on weight) can produce breathtakingly carrierlike landing distances.

Although aimed at the training market, the Seminole also appeals to a cadre of owner-operators who simply want a late-model multi for peace of mind when flying at night, over mountains, or over water. I can understand that. One of the best flying adventures I ever had was in a Turbo Seminole, only 87 of which were built. I flew N8264F, a demonstrator loaded with options — even weather radar — on a huge loop around the Caribbean, stopping at Stella Maris, South Caicos, Great Inagua, St. Thomas, St. Croix, Antigua, Martinique, Jamaica, and the Cayman Islands. The trip proved that the Seminole is as fine and capable a cruising machine as it is a trainer.

That was way back in 1981, when the Seminole was still a fresh concept and there was debate about whether the design would hang in there for the long run.

Performance Summary

The airplane is a four-place, low wing, twin engine airplane equipped with retractable tricycle landing gear.
This airplane is certified in the normal category. In the normal category all aerobatic maneuvers including spins are prohibited. The airplane is approved for day and night VFR/IFR operations when equipped in accordance with F.A.R. 91 or F.A.R 135.

The aircraft is powered by a Lycoming O-360-E1A6D and a LO-360-E1A6D, rated at 180 horsepower each. Both are four cylinder, normally aspirated, direct drive, air cooled, horizontally opposed, carburetor equipped engines.

Fuel is stored in two 55 gallon fuel tanks, one in each nacelle. The fuel tank vents, one installed under each wing, feature an anti-icing design to prevent ice formation from blocking the fuel tank vent lines. Auxiliary electric fuel pumps serve as a back up feature. Fuel quantities and pressures are indicated on gauges on the instrument panel. Fuel management controls are located on the console between the front seats. There is a control lever for each of the engines, and each is placarded “ON” – “OFF” – “X FEED.”

Electrical power is supplied by two 60 ampere alternators, one mounted on each engine. A 35 ampere-hour, 12-volt battery provides current for starting, for use of electrical equipment when the engines are not running, and for a source of stored electrical power to back up alternator output. An overvoltage relay in each alternator circuit prevents damage to electrical and avionics equipment.